With decreasing size of the packages used to house integrated circuits, the layout of printed wiring boards (“PWB's”) tends to become more crowded as well. A trend is to crowd more parts closer together. In such situations it may be difficult to provide sufficient bypassing on power supply lines coupled to the integrated circuits. Insufficient bypassing may limit the frequency response of the printed wiring board (“PWB”). Crowding the parts can also cause manufacturing difficulties such as tombstoning and the like.
FIG. 1 shows a conventional printed wiring board feed-through, pad and bypass capacitor (or “bypass cap”) layout 101. Today's layout techniques typically allow about 115 surface mount 0.0402 components per square inch due to the standard layout of solder pad and vias on a conventional printed wiring board. This pad/feed-through hole printed wiring board layout is typical of printed wiring layouts on the side of the printed wiring board that is opposite to the ball grid array (“BGA”) package. As shown a single pattern of a pair of feed-through holes and a pair of pads are stepped and repeated to form a printed wiring layout. Each set of pads allows mounting of a single bypass capacitor to the printed wiring board.
Dense packing may constrain the placement of bypass components on a printed wiring board. Traces are often fanned out away from the package to fit components into the space available. Also the close spacing of pads that couple to a ball grid array can limit the size and placement of feed-through holes utilized to carry signals between layer of the printed wiring board.